From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Monocoque versus sub-frame construction, focusing on insurance implications and repair costs.
| Identifier | ExFiles\Box 144\4\ scan0063 | |
| Date | 12th April 1940 | |
| To Sg.{Arthur F. Sidgreaves - MD} from Rm{William Robotham - Chief Engineer}/DB.{Donald Bastow - Suspensions} c. to Ev.{Ivan Evernden - coachwork} Myth Body & Frame Construction. This car is to be of monocoque construction. One of the first points to be decided is whether to bolt on the sub-frame or whether to weld everywhere. Do insurance Companies require higher premiums on cars without detachable sub frames? M.Olley has stated that G.M. would stick to a detachable sub-frame in order to avoid the payment of higher insurance rates. In "aspects of Frame Car Design" by W.D.Appel the following occurs :- "In neither England nor Germany are our (G.M.) cars subject to any higher insurance rates than if the car were of conventional construction. This condition we feel is principally due to the removable frame extension member which we use. Some other manufacturers who make this member an integral part of the body are subject to higher collision rates". Vauxhall demonstrated that the sub-frame was easily detachable to avoid higher insurance rates. Since the introduction of the Vauxhall ten Morris and Hillman have brought out models without detachable sub-frames. In May 1939 Morris staged a head on collision between two cars each travelling at over 30 m.p.h. One car was a Morris ten of monocoque construction and the other was an earlier Morris ten of conventional construction. The damage to the monocoque car was repaired in two days at a cost of £50. The cost of repairing the other car was at least £35. more. During the last few days I have made enquiries of nine insurance companies as to the cost of comprehensive policies on three 10 H.P. cars, one a vauxhall, having a bolted on sub-frame and two, Morris and Ford, having no | ||